Electrical system of distribution.



A-. s. HUBBARD. ELECTRICAL SYSTEM OI DISTRIBUTION.

APPLIQATIOH FILED JUNE 22, 190'! Patented Mar.21, 1911.

UNITED STATES PATENT OFFICE.

ALBERT S. HUBBARD, OF BELLEVILLE, NEW J 'IQRSEY, ASSIGNOR TO GOULDSTORAGE BATTERY COMPANY, A CORPORATION OF NEW YORK.

ELECTRICAL SYSTEM OF DISTRIBUTION.

Specification of Letters Patent.

Patented Mar. 21, 1911.

Application filed June 22, 1907. Serial No. 380,212.

To all whom it may concern:

Be it known that I, ALBERT S. HUBBARD, a citizen of the United States,and a resident of Belleville, Essex county, State of New Jersey, haveinvented certain new and use ful Improvements in Electrical Systems ofDistribution, of which the following is a specification.

My invention relates to electrical systems of distribution in whichstorage apparatus is arranged in operative relation to alternatingcurrent generators to act as a compensating influence to steady the loadof the generators. In such systems it is desirable to provide regulatingapparatus for controlling the action of the storage apparatus, suchregulating apparatus being governed by coils in the alternating currentcircuit In practice, however, the regulation of such storage apparatus,specifically storage batteries, by variations of current or load of thealternating current generators is unsatisfactory if the regulation issubstantially proportional to the current of the generator of thevoltage thereof or the product of the current and voltage. This is dueto the fact that in most systems of this character there is no definiterelation between the power factor of the circuit and the current orvoltthereof and the actual load on the generator is largely dependentupon the power factor of the circuit, or upon the proportion of thewattless energy to the apparent energy. I find, in practice, that anyregula tion of such a system having a varying and unpredictable powerfactor for any given current which involves no compensation for thechanges of power factor is extremely unsatisfactory.

By my invention I provide a storage battery constituting storageapparatus and regulate the action of the battery by a booster which isgoverned by changes of electrical conditioii of the main generator,while combining with the compensating action of the storage battery thecompensating action of a device which acts to give a varying condensanceor inductance, this device being connected to the alternating currentcircuit so that the inductance or condensance varies the power factor ofthat circuit, the inductance or condensance of this compensator beingcontrolled by the power factor changes of the circuit. Thus if there bea lagging current in the system the power factor compensator is made toact as a condensance and thus reduce the lag in the system. On the otherhand, if there be a lead in the system this compensator is made to actas an inductance and so offsets or reduces the lead of the current. thebattery is only regulated'in its action by apparent load changes, yetthe generator may be kept within comparatively close limits of actualload changes because the power factor compensator, acting independentlyof the battery, prevents any wide variation between the apparent loadand the actual load.

The power factor compensator may be a large synchronous motor revolvingfreely, its field strength being regulated so that its armature,connected to the alternating current system, will act as a condensancewhen the field strength is great and as an inductance when the fieldstrength is small. I control the field strength of the synchronous motoror power factor compensator by supplying a direct current excitingcurrent that is obtained from a converter connected to the alternatingcurrent circuit to receive a current that is responsive to the currentchanges in the system. This converter is one that has been described andclaimed in an application filed by me July 2, 1906, Serial No. 324,393.This is a device having windings and magnetic induction but devoid ofmotor action, being driven in synchronism with the electro motive forceof the main generator and having a commutator upon which are two sets ofbrushes, one set being placed. at points of normal (when the powerfactor is unity) maximum difference of potential, and the other setbeing placed at the points of normal minimum difference of potential.The current to the converter is supplied by series transformers in themains of the system. When the power factor varies the two sets ofbrushes are no longer at the points of maximum and minimum difierence ofpotential so that the current flows in one direction or another from thelatter set of brushes, varying in direction according to whether thecurrent of the system is a leading or a lagging one, and varying indegree according to the amount of current in the system and the amountof the lead or lag of said current. The current from this set of brushesvaries in accordance with the wattless energy The result is that even ifthereof. It is this current that is employed for varying the field ofthe synchronous motor acting as a power compensator.

In its broader phase my invention comprises the employment of a storageapparatus regulated by current changes in operative relation \with analternating current generator and an independent power factorcompensator controlled automatically to limit the power factorvariations of the system.

More specifically my invention involves the more specific features aboveoutlined and more fully described hereinafter.

According to my invention I may employ the circuit connected to that setof the brushes of the commutator of the converter which bear upon thepoints of normal max mum difference of potential either as a bypass, anadjustable resistance being in the by-pass circuit, or as a source ofregulation for the storage battery. In the latter case the battery willbe regulated responsively not merely to current or apparent loadvariations of the alternating current load of the generator, but indefinite relation to the true energy changes thereof. In this case theindependent power factor compensator regulated by the other circuit fromthe converter will, as before, limit power factor changes on the systemwhile the storage battery will be regulated to compensate for suchchanges of power factor as still exist.

Where the translating devices and the generators are considerabledistance apart it is preferable to connect the power factor compensatorand its regulating apparatus at the part of the system to which thetranslating devices are connected, while the compensating battery andits regulating apparatus may be placed at any convement point, either atthe main generating station or at the end of the transmission line.

My i vention makes possible the employment 0 a main generator station ofthe compensating storage apparatus and of in"- dependent power factorcompensators at various parts of the system.

My invention involves the foregoing features and also the more specificfeatures of construction and arrangement and combination which will bemore fully described hereinafter.

The drawing is a diagram illustrating a system of distribution to whichone specific embodiment of my invention-is applied.

A represents a main alternating current generator shown as a three phasegenerator. This may be considered indicative of one or any number ofgenerators and it is immaterial whether this generator is in the mainstat-ion of the system or a sub-station and whether it is a prime sourceof electricity of what character of source it may be so long as itsupplies to the system or to a part of the whole system an alternatingcurrent for some commercial purpose.

B is a recifier connected to the alternating current circuit of thegenerator A and to a direct current circuit and serving as a means fortransferring energy from either circuit to the other.

Cis a storage battery in which part of the energy of the generator A isto be stored during period of light load and which is to give out energyto the translating devices during periods of heavy load. The translatingdevices may be connected either to the alternating current conductors 1,2, 3, or to the direct current conductors 4, 5, or to both. The systemmay be such, if the translating devices are largely or wholly connectedto the direct current side, that energy will never be transferred fromthe battery to. the alternatingcurrent side of the system, or it may besuch that during times of battery discharge the current from thebattery, or a part of it, will be transferred into the rectifier B andsupply energy to the alternating current translating devices.

D is a booster in series with the battery 0 and regulated fromintervening apparatus responsively to electrical conditions of thealternating current circuit.

E is the power factor compensator being in the present instance a largesynchronous motor having a field winding E constantly excited from theexciter F and a second or regulating field winding E the current inwhich is to be regulated by intervening apparatus in definite relationto the power factor changes of the system.

The power factor compensator E and the storage battery G are inoperative relation with the alternating current circuit, the formerbeing connected directly thereto and the latter because it is connectedto the converter or rectifier B.

F is a motor to drive the booster D.

I have illustrated in the drawing the battery and compensator as beingregulated by the variations occurring at the same point in the system,such regulation being efiiected in part by the same apparatus, but suchapparatus acts to produce the different regulating effects upon thebattery and compensator that my invention involves.

G, G, G, are series transformers in the circuit of the main generator Aso that the current given out by the secondaries of these tranformers(which in the present instance are indicated as star connected) willvary in accordance with the current variations of the main generator.

H is a rectifier or converter which, as indicated, is provided withwindings and a commutator, the three secondaries of transformers Grbeing connected to the windings at points 120 apart. This rectifier willhave magnetic induction and is preferably constructed with magneticmaterial, but it is devoid of motor or generator action, which isattained in the present instance by having no external field magnet.Such a rectifier has been shown and described more in detail in thepatent to Edward Van Wagenen, 869,279, October 29th 1907. The rectifierH is mechanically connected, as indicated, with a synchronous motor Jwhich, to obtain the best result, should be constructed to operate inclose synchronism with the generator. The converte r H is thereforedriven in synchronism with the electro-motive-force of the alternatingcurrent circuit. The current supplied from transformers G to the windingof converter H produces a rotating field which rotates in synchronismwith the current of the alternating current circuit. \Vhen theelectro-motive-force and current of the alternating current circuit arein phase, the rotating field will be stationary in space at a definiteposition, whereas the position of this rotating field will vary wheneverthe phase relation of the electromotiveforce and current vary.

it are brushes bearing upon the commutator h of the converter H atpoints of substantially maximum difference of potential when the currentand electro-motive-force of the alternating current circuit are inphase, 6., when the power factor is unity.

]L2 are brushes bearing upon commutator h at points substantially 90electrical degrees from brushes h and therefore at points ofsubstantially equal potential when the power factor is unity. When,therefore, the power factor of the alternating current circuit is unity,the current in any circuit connected to brushes 7 will be in a givenproportion to the current in the alternating current circuit, while thecurrent in any circuit connected to brushes 7L will be zero. If,however, there is a leading current in the alternating current circuit,the brushes h will no longer be at the points of maximum difierence ofpotential, nor will the brushes k be at points of substantially equalpotential. For this reason a current in the circuit of brushes 7L willbe smaller relatively to that of the alternating current circuit thanwhen the power factor is unity, while a current whose strength, relativeto that of the alternating current circuit, will depend upon the extentof lead, will flow in the circuit of the brushes 7f. Vfhen there is alag of the current in the alternating current circuit, the same resultsare produced except that the current in the circuit of the brushes 72will be in the opposite direction.

It will be seen that the current in the circuit of the brushes It willvary in proportion to the true energy components of the apparent energy,while the current in the circuit of the brushes 71, will vary inaccordance with variations of the wattless energy components of theapparent energy. In the specific system shown, I have em ployed thecurrent produced in the circuit of the brushes h. as a regulatingcurrent for the battery, whereby the battery action is regulated inaccordance with changes of true energy components of the apparent energyof the alternating current circuit, while I have used the current in thecircuit of the brushes k as a regulating current for the power factorcompensator so that it may be regulated in accordance with the wattlessenergy changes of the circuit and thereby limit the variations of powerfactor in that circuit.

The regulation of the battery action is effected by the variations ofcurrent in the circuit of brushes h by causing such current to circulatein field coil K of a counter machine K, mechanically connected to thebooster D and motor F, which counter inachine is in circuit with thefield coil D of the booster, the two being connected in a local circuitacross the direct current side of the system. Assuming that theapparatus is adjusted so that forthe average actual load upon the maingenerator A, the voltage of booster D will be zero and the battery willbe floating across the direct current side of the system neithercharging nor discharging, then at this average condition of the maingenerator the current in the coil K will be such as to produce anelectro-motive-force in the counter machine K that will equal theopposing electro-motive-force of the direct current side of the system.If by a change of current from the main generator, or by a change in thepower factor, or by both combined, the actual load (assuming un changedvoltage of the main generator) becomes changed, then there will be acorresponding change in the current of the field K and a definitelyrelated change in the current of the field D of the booster, thuscausing the booster to produce an electromotive-force that will assistto charge or discharge the battery according to whether the change inthe actual load on the main generator was a decrease or an increase.Changes of the wattless energy of the circuit of the generator A arewithout substantial effect upon the control of the booster because thatpart of the apparent energy which corresponds to the wattless energy ofthe circuit causes a part of the current from the transformers G to beby-passed to the circuit connected with the brushes 71.

The current from the brushes 7L2 supplies the regulating field winding Eof the synchronous motor or puower factor compensator E. When the powerfactor is unity so that there is no current in the field winding E thefield winding E will give a field strength to the motor E that willcause such motor to act neither as an inductance nor as a condensance.When, however, there is a' leading current, the current in the circuitof the brushes [L2 is in such direction as to cause the coil E to be adifferential coil, thus weakening the field strength of the synchronousmotor and causing it to act as an inductance to oppose the condcnsanceof the remaining portion of the system and lessen the lead. 0n the otherhand, if the current in the alternating current circuit be a laggingone, the coils E and E act cumulatively and cause the synchronous motorto act as a condensance to oppose the inductance of the other portionsof the alternating current circuit and reduce the lag therein. By thesystem illustrated therefore the battery and power factor compensatorare independently regulated, the former being regulated to maintain asubstantially constant real load upon the main generator, while thelatter is regulated to steady the power factor of the circuit of themain generator and thus avoid large wattless energy currents.

Many specific methods and apparatus have been provided to regulatestorage batteries either for alternating current or for direct currentgenerators and it is not material to this invention what particularmethod or apparatus employed for this purpose. Moreover, it is notimportant to my invention whether such regulation as is given to thebattery is a regulation by current changes or energy changes or voltagechanges, such matters being variations that depend upon the particularconditions to be met, as well being matters of engineering choice andall coming within my invention be in the opposite direction.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is,-

1. In an electrical. system of distribution an alternating currentcircuit, a power fac-t tor compensator therefor, a storage apparatusoperatively connected with the circuit and an electric device excited bycurrents responsive to changes in the electrical condition of thecircuit, said device being arranged and having connections to producetwo currents, one for the regulation of the power factor compensator andthe other for the regulation of the storage apparatus.

2. The combination of an alternating current circuit, a power factorcompensator therefor, a storage apparatus operatively related to thecircuit and an electric machine operating responsive to changes in theelectrical condition of said circuit having connections and arranged toregulate both the compensator and storage apparatus.

3 The combination of an alternating curp lated to the circuit, arectlfier connected to rent circuit, a power factor compensatortherefor, a storage apparatus operatlvely related to the clrcult and asynchronously driven electric machine carrying current responsive tocurrent changes of the system and arranged to produce currents whichregulate the compensator and storage apparatus.

4. The combination of an alternating current circuit, a power factorcompensator therefor, a storage apparatus operatively related to thecircuit and a device operatively related to the circuit and arranged toproduce a current responsive to wattless energy changes of the circuitfor regulating the compensator, and a current responsive to true energychanges of the circuit for regulating the storage apparatus.

5. '1 1e combination of an alternating current circuit, a power factorcompensator therefor, a storage apparatus operatively related to thecircuit, means operatively related to the alternating current circuitand arranged to produce a current responsive to variations of thewattless energy of the circuit and a current responsive to true energyvariations of the circuit and means arranged whereby the storageapparatus is regulated by one of said currents and the power factorcompensator by the other of said currents.

6. The combination of an alternating cur rent circuit, a power factorcompensator therefor, a storage apparatus operatively related to thecircuit, means operatively related to the alternating current circuitand arranged to produce a current responsive to variations of thewattless energy of the circuit and a current responsive to true energyvariations of the circuit, a controlling coil on the compensatorenergized by said first mentioned current and a coil excited by saidsecond mentioned current and arranged to regulate the storage apparatus.

7. The combination of an alternating current circuit, a power factorcompensator therefor, a storage apparatus operatively related to thecircuit, a rectifier connected to receive alternating current varyingwith that of the alternating current circuit arranged to produce arotary magnetic field driven in synchronism with the electronictiveforce of the alternating current circuit, a commutator on the rectifier,a pair of brushes on the commutator normally at points of substantiallyequal potential, a pair of brushes on the commutator normally at pointsof maximum difference of potential, a coil connected to said firstmentioned brushes and arranged to regulate the compensator and a coilconnected to the last mentioned brushes and arranged to regulate thestorage apparatus.

8. The combination of an alternating current circuit, a power factorcompensator therefor, a storage battery operatively rereceivealternating current varying with that of the alternating currentc1rcu1t, a commutator on the rectifier, a pair of brushes on thecommutator normally at points of substantially equal potential, a pairof brushes on the commutator normally at points of maximum difl erenceof potential, and a coil connected to each pair of brushes, one of saidcoils being arranged to control the action of the power factorcompensator and the other coil being arranged to control the action ofthe battery.

9. The combination of an alternating current circuit, a power factorcompensator and a storage battery in operative relation thereto, anelectric apparatus having windings energized by current responsive tocurrent changes of the circuit and brushes rotated relatively to saidwindings in synchronism with the voltage of the circuit, said apparatusbeing arranged to produce two currents and means arranged whereby one ofthe currents regulates the action of the, storage battery and the otherof said currents regulates the action of the compensator.

10. The combination of an alternating current circuit, means forproducing a condensance arranged to regulate the circuit for powerfactor changes thereof, a com pensatory storage battery in operativerela' tion to the circuit, an electric apparatus having windingsenergized by current responsive to current changes of the circuit andbrushes rotated relatively to said windings in synchronism with thevoltage of the circuit, said apparatus being arranged to produce twodirect currents, one responsive to wattless energy changes of thecircuit and the other responsive to true energy changes of the circuit,and means whereby said first mentioned current regulates the action ofsaid means for producing the condensance and said second mentionedcurrent regulates the action of the battery.

11. The combination of an alternating current circuit, seriestransformers operatively arranged with respect thereto, a power factorcompensator and compensatory storage battery in operative relationthereto, and a rectifier excited by current from transformers connectedin series in said circuit, said rectifier having a part rotatable insynchronism with the voltage of the circuit and said rectifier beingarranged to produce cur rents for regulating both the power factorcompensator and the storage battery.

12. The combination of an alternating current circuit, a power factorcompensator operatively related thereto and arranged to maintain thepower factor of the circuit at substantially unity and a storageapparatus operatively related to the circuit and means for regulatingthe storage apparatus responsive to current changes of the circuit, saidmeans including an apparatus for producing a current responsive to trueenergy changes of the circuit with varying power factor whereby thebattery is regulated by substantially true energy changes of thecircuit.

13. The combination of an alternating current circuit, a power factorcompensator therefor, a storage apparatus operatively related to thecircuit, means operatively related to the alternating current circuitand arranged to produce two currents, one responsive to current changesof the current of the circuit, and means whereby the storage apparatusis regulated by this last mentioned current and means whereby thecompensator is regulated by the other current.

14. The combination of an alternating current circuit, a power factorcompensator therefor, a storage apparatus operatively related to thecircuit, apparatus operatively related to the alternating currentcircuit and arranged to produce two currents, one responsive to currentchanges of the current of the circuit, and the other responsive to powerfactor changes of the circuit, means whereby the storage apparatus isregulated by said first mentioned current and means whereby saidcompensator is regulated by said last mentioned current so that thebattery is substantially regulated by true energy changes of thecircuit.

In testimony whereof, I have signed my name to this specification, inthe presence of two subscribing witnesses.

ALBERT S. HUBBARD.

Witnesses:

EDWIN SEGER, ANNA DALY.

Copies of this patent may be obtained for five cents each, by addressingthe "Commissioner of Patents, Washington, I). G.

